Commit e716efde authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

genirq: Avoid deadlock in spurious handling 



commit 52553ddf(genirq: fix regression in irqfixup, irqpoll)
introduced a potential deadlock by calling the action handler with the
irq descriptor lock held.

Remove the call and let the handling code run even for an interrupt
where only a single action is registered. That matches the goal of
the above commit and avoids the deadlock.

Document the confusing action = desc->action reload in the handling
loop while at it.

Reported-and-tested-by: default avatar"Wang, Warner" <warner.wang@hp.com>
Tested-by: default avatarEdward Donovan <edward.donovan@numble.net>
Cc: "Wang, Song-Bo (Stoney)" <song-bo.wang@hp.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 04aa530e

kernel/irq/spurious.c

+3 −4
Original line number Diff line number Diff line
@@ -80,13 +80,11 @@ static int try_one_irq(int irq, struct irq_desc *desc, bool force) 


	/*

	 * All handlers must agree on IRQF_SHARED, so we test just the

	 * first. Check for action->next as well.

	 * first.

	 */

	action = desc->action;

	if (!action || !(action->flags & IRQF_SHARED) ||

	    (action->flags & __IRQF_TIMER) ||

	    (action->handler(irq, action->dev_id) == IRQ_HANDLED) ||

	    !action->next)

	    (action->flags & __IRQF_TIMER))

		goto out;



	/* Already running on another processor */
@@ -104,6 +102,7 @@ static int try_one_irq(int irq, struct irq_desc *desc, bool force) 
	do {

		if (handle_irq_event(desc) == IRQ_HANDLED)

			ret = IRQ_HANDLED;

		/* Make sure that there is still a valid action */

		action = desc->action;

	} while ((desc->istate & IRQS_PENDING) && action);

	desc->istate &= ~IRQS_POLL_INPROGRESS;